docs: def point_in_tetrahedron(tetra, pt):
      '''
      point_in_tetrahedron(tetrahedron, point) yields True if the given point is in the given 
        tetrahedron. If either tetrahedron or point (or both) are lists of shapes/points, then this
        calculation is automatically threaded over all the given arguments.
      '''
      bcs = tetrahedral_barycentric_coordinates(tetra, pt)
      return np.logical_not(np.all(np.isclose(bcs, 0), axis=0))